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A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.
- a)2.5
- b)3.0
Correct answer is between '2.5,3.0'. Can you explain this answer?
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Verified Answer
A steel pipe of 20 mm inner diameter and 2 mm thickness is covered wi...
R1 = 10 mm ; r2 = 10 + 2 = 12 mm and r3
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= 12 + 20 = 32 mm
The thermal resistance to flow of heat are offered by
The heat transfer through the insulated pipe is than given by
The thermal conductivity of steel pipe is not given, and generally it is much higher than that of insulation. Accordingly thermal resistance due to pipe material can be neglected
That gives:
if Ui is the overall heat transfer coefficient based on inside surface area of the steel pipe, then heat flow rate can also be written as
comparing identities 
and
, we note that
and , we note thatUpon substitution of given data,
Most Upvoted Answer
A steel pipe of 20 mm inner diameter and 2 mm thickness is covered wi...
Given data:
Inner diameter of steel pipe = 20 mm
Thickness of steel pipe = 2 mm
Thickness of fiberglass insulation = 20 mm
Conductive coefficient of fiberglass insulation (k) = 0.05 W/m-°C
Inside convective coefficient (hi) = 10 W/m2-°C
Outside convective coefficient (ho) = 5 W/m2-°C
To find: Overall heat transfer coefficient based on inside diameter of the pipe
Solution:
1. Thermal resistance of steel pipe:
The thermal resistance of the steel pipe can be calculated using the formula:
R1 = ln(ro/ri)/(2πk1L)
where,
ro = outer radius of the steel pipe = ri + 2t = 20 + 2(2) = 24 mm = 0.024 m
ri = inner radius of the steel pipe = 20 mm = 0.02 m
t = thickness of the steel pipe = 2 mm = 0.002 m
k1 = thermal conductivity of steel = 45 W/m-°C
L = length of the pipe = 1 m
R1 = ln(0.024/0.02)/(2π×45×1) = 0.000926 °C/W
2. Thermal resistance of fiberglass insulation:
The thermal resistance of the fiberglass insulation can be calculated using the formula:
R2 = ln(r2/r1)/(2πk2L)
where,
r2 = outer radius of the insulation = ri + 2t + di = 20 + 2(2) + 0.02 = 24.04 mm = 0.02404 m
r1 = inner radius of the insulation = ri + t = 20 + 2 = 22 mm = 0.022 m
di = inner diameter of the insulation = 20 mm = 0.02 m
k2 = thermal conductivity of fiberglass insulation = 0.05 W/m-°C
L = length of the pipe = 1 m
R2 = ln(0.02404/0.022)/(2π×0.05×1) = 0.0948 °C/W
3. Thermal resistance of inside film:
The thermal resistance of the inside film can be calculated using the formula:
R3 = 1/(hiA)
where,
A = area of the inner surface of the pipe = πdiL = π×0.02×1 = 0.0628 m2
R3 = 1/(10×0.0628) = 0.159 °C/W
4. Thermal resistance of outside film:
The thermal resistance of the outside film can be calculated using the formula:
R4 = 1/(hoA)
where,
A = area of the outer surface of the insulation = πr2L - πriL = π(0.02404)×1 - π(0.02)×1 = 0.0757 m2
R4 = 1/(5×0.0757) = 0.2638 °C/W
5. Overall thermal resistance:
The overall thermal resistance can be calculated by adding all the thermal resistances:
Rtotal = R1 + R2 + R3 + R4 = 0.000926 + 0.0948 + 0
Inner diameter of steel pipe = 20 mm
Thickness of steel pipe = 2 mm
Thickness of fiberglass insulation = 20 mm
Conductive coefficient of fiberglass insulation (k) = 0.05 W/m-°C
Inside convective coefficient (hi) = 10 W/m2-°C
Outside convective coefficient (ho) = 5 W/m2-°C
To find: Overall heat transfer coefficient based on inside diameter of the pipe
Solution:
1. Thermal resistance of steel pipe:
The thermal resistance of the steel pipe can be calculated using the formula:
R1 = ln(ro/ri)/(2πk1L)
where,
ro = outer radius of the steel pipe = ri + 2t = 20 + 2(2) = 24 mm = 0.024 m
ri = inner radius of the steel pipe = 20 mm = 0.02 m
t = thickness of the steel pipe = 2 mm = 0.002 m
k1 = thermal conductivity of steel = 45 W/m-°C
L = length of the pipe = 1 m
R1 = ln(0.024/0.02)/(2π×45×1) = 0.000926 °C/W
2. Thermal resistance of fiberglass insulation:
The thermal resistance of the fiberglass insulation can be calculated using the formula:
R2 = ln(r2/r1)/(2πk2L)
where,
r2 = outer radius of the insulation = ri + 2t + di = 20 + 2(2) + 0.02 = 24.04 mm = 0.02404 m
r1 = inner radius of the insulation = ri + t = 20 + 2 = 22 mm = 0.022 m
di = inner diameter of the insulation = 20 mm = 0.02 m
k2 = thermal conductivity of fiberglass insulation = 0.05 W/m-°C
L = length of the pipe = 1 m
R2 = ln(0.02404/0.022)/(2π×0.05×1) = 0.0948 °C/W
3. Thermal resistance of inside film:
The thermal resistance of the inside film can be calculated using the formula:
R3 = 1/(hiA)
where,
A = area of the inner surface of the pipe = πdiL = π×0.02×1 = 0.0628 m2
R3 = 1/(10×0.0628) = 0.159 °C/W
4. Thermal resistance of outside film:
The thermal resistance of the outside film can be calculated using the formula:
R4 = 1/(hoA)
where,
A = area of the outer surface of the insulation = πr2L - πriL = π(0.02404)×1 - π(0.02)×1 = 0.0757 m2
R4 = 1/(5×0.0757) = 0.2638 °C/W
5. Overall thermal resistance:
The overall thermal resistance can be calculated by adding all the thermal resistances:
Rtotal = R1 + R2 + R3 + R4 = 0.000926 + 0.0948 + 0
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A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer?
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A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer? for Chemical Engineering 2024 is part of Chemical Engineering preparation. The Question and answers have been prepared according to the Chemical Engineering exam syllabus. Information about A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer? covers all topics & solutions for Chemical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer?.
A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer? for Chemical Engineering 2024 is part of Chemical Engineering preparation. The Question and answers have been prepared according to the Chemical Engineering exam syllabus. Information about A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer? covers all topics & solutions for Chemical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer?.
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A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer?, a detailed solution for A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer? has been provided alongside types of A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick fiberglass insulation(k = 0.05 W/m-°C). If the inside and outside convective coefficients are 10 W/m2-°C and 5W/m2-°C , calculate the overall heat transfer coefficient based on inside diameter of the pipe.a)2.5b)3.0Correct answer is between '2.5,3.0'. Can you explain this answer? theory, EduRev gives you an
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